Twenty Fifteen: Search field clear button misaligned

[johnbillion]

The x which appears in the search field in the sidebar is misaligned in Safari on OS X.

[lancewillett]

Remove webkit rules and let Safari style be as the browser chrome itself expects

[lancewillett]

Attempt to simplify padding for all search inputs

[lancewillett]

New patch attempts to simplify the padding for all search input elements throughout the stylesheet.

[lancewillett]

Better replacement of all top/bottom padding values in search input rules

[lancewillett]

.2 is more intelligent replacement of top/bottom/left padding values for all search input rules.

Related CSS style note: all values in CSS with a starting 0 in front of a decimal place can be removed: 0.6154em should be .6154em instead for simplicity.

[lancewillett]

In 30945:

Twenty Fifteen: hide search input cancel button. See #30728.

[lancewillett]

Discussing the leading zero for unit values -- per ​https://make.wordpress.org/core/handbook/coding-standards/css/#values WP style guide we should leave them as-is.

[johnbillion]

In 30947:

Twenty Fifteen: hide search input cancel button.

Merges [30945] to the 4.1 branch.

Fixes #30728.